Overview
Microcephalic osteodysplastic primordial dwarfism types I and III (MOPD I/III), also known as Taybi-Linder syndrome, is an extremely rare autosomal recessive disorder characterized by severe intrauterine and postnatal growth restriction, microcephaly, and skeletal dysplasia. Types I and III were historically described separately but are now recognized as the same condition. The disorder is caused by biallelic mutations in the RNU4ATAC gene, which encodes a small nuclear RNA component of the minor spliceosome, essential for proper mRNA splicing. Affected individuals present with severe prenatal-onset dwarfism, marked microcephaly with a sloping forehead, sparse hair, dry and wrinkled skin, and distinctive facial features including a prominent nose and micrognathia. Skeletal abnormalities are prominent and include short bowed long bones, platyspondyly (flattened vertebral bodies), and metaphyseal flaring. Brain malformations such as lissencephaly, agenesis of the corpus callosum, and cerebellar hypoplasia are frequently observed. Additional features may include low-set ears, short limbs, and intellectual disability in those who survive. The prognosis for MOPD I/III is very poor, with most affected individuals dying in infancy or early childhood, often within the first year of life, due to complications including recurrent infections and respiratory failure. There is no specific curative treatment; management is supportive and symptomatic, focusing on nutritional support, management of infections, and addressing individual complications as they arise. Genetic counseling is recommended for affected families.
Also known as:
Clinical phenotype terms— hover any for plain English:
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Neonatal
Begins at or shortly after birth (first 4 weeks)
FDA & Trial Timeline
1 eventHospices Civils de Lyon — NA
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Microcephalic osteodysplastic primordial dwarfism types I and III.
1 clinical trialare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Rare Disease Specialist
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Microcephalic osteodysplastic primordial dwarfism types I and III.
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Start the conversation →Latest news about Microcephalic osteodysplastic primordial dwarfism types I and III
Disease timeline:
New trial: Study of the Pathophysiology of RNU4ATAC and RTTN Associated Syndromes
Phase NA trial recruiting. Blood samples
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Common questions about Microcephalic osteodysplastic primordial dwarfism types I and III
What is Microcephalic osteodysplastic primordial dwarfism types I and III?
Microcephalic osteodysplastic primordial dwarfism types I and III (MOPD I/III), also known as Taybi-Linder syndrome, is an extremely rare autosomal recessive disorder characterized by severe intrauterine and postnatal growth restriction, microcephaly, and skeletal dysplasia. Types I and III were historically described separately but are now recognized as the same condition. The disorder is caused by biallelic mutations in the RNU4ATAC gene, which encodes a small nuclear RNA component of the minor spliceosome, essential for proper mRNA splicing. Affected individuals present with severe prenata
How is Microcephalic osteodysplastic primordial dwarfism types I and III inherited?
Microcephalic osteodysplastic primordial dwarfism types I and III follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Microcephalic osteodysplastic primordial dwarfism types I and III typically begin?
Typical onset of Microcephalic osteodysplastic primordial dwarfism types I and III is neonatal. Age of onset can vary across affected individuals.
Are there clinical trials for Microcephalic osteodysplastic primordial dwarfism types I and III?
Yes — 1 recruiting clinical trial is currently listed for Microcephalic osteodysplastic primordial dwarfism types I and III on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat Microcephalic osteodysplastic primordial dwarfism types I and III?
1 specialists and care centers treating Microcephalic osteodysplastic primordial dwarfism types I and III are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.